Bacillus subtilis DNA replication origin containing fragment isolated by restriction enzyme cleavage will be ligated to plasmid PUB110 DNA which carries the gene for neomycin resistance. The chimeric plasmid will be propagated in a B. subtilis carrying recE, dnaC mutations. The isolated origin fragment will be used for in vitro replication studies and also to make DNA cellulose column that would permit the isolation of proteins involved in initiation of replication. The same approach will be used to amplify the phage SPP1 DNA replication origin and the gene that codes for a factor which modifies the specificity of DNA Polymerase III of the host. The process of replication using in vitro modified Pol III will be analyzed. The study of newly induced restriction-modification system in b. subtilis genetics recombination will be continued. In parallel the mechanisms of DNA mediated transformation of mammalian cells are also being pursued.